Knitted muscles hold promise for assisted mobility
Fabric coated with electroactive material has been shown to actuate like muscle fibres and could be incorporated into clothes in order to improve movement for people with disabilities.
Researchers at Linköping University and the University of Borås in Sweden used lightweight, flexible fabric, and coated it with an electroactive material to create what they call “textile muscles”.
A low voltage applied to the fabric causes the electroactive material to change volume, causing the yarn or fibres to increase in length. The properties of the textile are controlled by its woven or knitted structure.
Robot technology and prostheses have developed rapidly in recent years due to technological breakthroughs.
For example, devices known as ‘exoskeletons’ that act as an external skeleton and muscles have been developed to reinforce a person’s own mobility.
“Enormous and impressive advances have been made in the development of exoskeletons, which now enable people with disabilities to walk again,” said Edwin Jager at Linköping University.
“But the existing technology looks like rigid robotic suits. It is our dream to create exoskeletons that are similar to items of clothing, such as ‘running tights’ that you can wear under your normal clothes.
“Such devices could make it easier for older persons and those with impaired mobility to walk.”
The researchers have already shown how the textile muscles can be used in a simple robot device to lift a small weight.
They demonstrate that the technology enables new ways to design and manufacture devices known as ‘actuators’, which – like motors and biological muscles – can exert a force.
“If we weave the fabric, for example, we can design it to produce a high force. In this case, the extension of the fabric is the same as that of the individual threads,” said Nils-Krister Persson, at the University of Borås.
He explained that the force developed by the fabric is much greater when the threads are connected in parallel in the weave in a similar fashion to human muscles. He also proposed using an extremely stretchable knitted structure for certain use cases that could increase the effective extension of the fabric.
“Our approach may make it possible in the long term to manufacture actuators in a simple way and hopefully at a reasonable cost by using already existing textile production technologies. What’s more interesting, however, is that it may open completely new applications in the future, such as integrating textile muscles into items of clothing,” Jager said.
In September, a California-based team demonstrated a plastic-based textile material that could efficiently cool the body in hot surroundings.